The use of salt solution has supplanted the _transfusion of blood_. This requires a source of blood which is not always at hand and an amount of attention which can rarely be given in emergencies; moreover, it has been shown that the injection even of defibrinated blood is a dangerous procedure, because of liberation of hemoglobin and destruction of white corpuscles, with the liability to coagulation of the blood from increase of fibrin ferment, and the possible death of the patient. Direct transfusion from another person into the veins of the patient is also difficult, and has rarely been of service. As already stated in the chapter on Shock, the best solution for infusion is composed of calcium chloride 2 parts, potassium chloride 3 parts, sodium chloride 9 parts, sterile water, 1000 parts. The addition of one part of sodium bicarbonate will sometimes prove of advantage, while in diabetic cases this may be increased to three parts to a thousand. It has also been suggested to add a small proportion of sugar, even up to thirty parts, to this solution, in order to increase osmotic action and better preserve the red corpuscles from injury. It is supposed also to give a certain nutritive value. When the fluid is injected into the venous system all that is desired is that it barely enter; consequently the receptacle containing the fluid should be held but a few inches above the level of the opening. When hypodermoclysis is practised more pressure will be needed and a greater difference of level should be maintained. In the veins the amount injected should not exceed 100 Cc. each minute. From 500 to 1500 Cc. may be used altogether. There need be no hesitation in introducing it at a temperature considerably above the body normal, and in cases of shock it may be introduced even at 115° F. The character of the pulse will afford the indication as to the amount of fluid to be used as well as the wisdom of repeating the measure after an interval. For _intravenous infusion_ a vein in the arm is usually exposed and the needle point carefully inserted. It is an advantage to have for this purpose a special needle, made with a blunted extremity, enlarged a little, so that by the use of a temporary ligature the vein may be held tightly around the cannula, for such it really is, and the escape of fluid be prevented. After withdrawal of the needle a double ligature should be placed for purposes of security. The limb should also be kept at rest for a few days.